I have found 2 things which work for me:
the patch (scopalomine), which needs to be applied 4 hours before the problem starts. It works well for me, but causes dry throat and sleepiness.
The sleepiness was never so bad that I could not perform my crew duties.
I have used this on several cruises and it has really helped me.
The patch requires a prescription in the US, but can be bought over the counter in Italy.
The second is a chewing gum that is available in Europe,
Trawell. One time when we had been surfing down big swells for half the day and I was really feeling green and not interested in much, after chewing this gum for 10 minutes I took the helm and was fine.
[Disclosure: I have no financial or other interest in either remedy.

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